I decided to send my tune into AA for the flash since there were no dealers with flash stations near me, and the whole process was a pain in the ass. It would've been less of a pain in the ass if AA would've provided clearer instructions other than "follow our E9X M3 ECU removal guide which should be the same," because removing the ECU from an E9X non-M3 is NOT the same as removing the ECU from an E9X M3. Thankfully for the e90post forums, I received help from user ja. who provided me with a JB4 installation video which helped me access the ECU.

I shipped my ECU out to AA, and it was promptly returned.

Reinstallation and Start Up

Simple enough -- just reverse the steps for removal to get the ECU back in, as stated in the instructions provided by AA.

What AA doesn't state is that you're supposed to turn the car on to position 2 (key in with two presses of the ignition -- lights on, etc.) for 20 seconds so the ECU can re-adapt to the car. I only found out by calling AA after my car went crazy and suffered in the process, and only then was I informed about this "ECU adaptation process."

With my newly flashed ECU in, I started my engine.

Start 1: The engine fluttered, rose up to 4K RPM, and died with all error lights on -- CEL, 4x4, everything.

Start 2: The engine fluttered between 2K to 4K RPM, up and down, up and down. I pressed the throttle, but no response.

Start 3: The engine fluttered, but settled down to 1K RPM. I pressed the throttle to check if it was working, and I got a loud "POP" and cloud of black smoke out of my exhaust. The car was running and working, or so I had hoped. My CEL remained on, but I decided to take it for a drive.

The Drive

My first thought was "this was the biggest waste of $450." I was feeling regretful that I didn't feel much of a difference in performance, and I was feeling especially regretful that I had gone though so much trouble just before this initial test run. I was afraid that this would become more of a "convince myself that my $450 was well spent placebo effect." I ran a round of errands, which included going to AutoZone to get my error codes cleared, and totaled 30 miles on the new ECU, still feeling unimpressed. AA states the ECU takes 50-100 miles to fully adapt, so I kept my hopes up and gave it a chance to break in.

The next day, I put over 200 miles on the new ECU, and was feeling more of a difference in performance. It isn't a HUGE difference as I'm still trying to figure out how different the car really is compared to stock. Maybe I had set my hopes too high... I thought this tune would've blown my mind as it did for some members on the forum. No, I don't mean feeling as if I went from a 328 to a 335, but I've come across some very promising reviews.

What I've noticed is that my car does pull a little harder in the lower RPM range (especially in second and third gears where the car used to feel very sluggish), and there's a point after 3.5K or 4K where it opens up much more than it used to. The throttle feels more responsive, and pulls feel smooth. There's undoubtedly a difference. It may be small/minute, but it's there.

The car now feels "right," meaning it feels like it should've come from the factory this way. It'll add some pep to your step, but not enough to set a stock N51 worlds apart from an AA tuned N51. Again, my pre-tune and post-tune drives were done almost two weeks apart, so maybe I would've felt more of a difference if I had made the drives back to back. It's a great mod, I have no regrets, and the tune will add some enjoyment to your driving, but I still stand by my belief that the best mod I've done to my car is my BMW Performance Exhaust with secondary cat delete. Now that's an enjoyable and definitely noticeable mod.